Abstract: A single crystal turbine blade has a portion of its attachment section layered with a fine grained, poly-crystalline alloy. The blade is prepared by casting a single crystal body with an undersized attachment section, and then layering the attachment section with the poly-crystalline superalloy to form a composite structure. Layering is preferably accomplished by plasma spraying the body with the superalloy, and hot isostatically compacting the sprayed superalloy to minimize porosity. The composite structure is then heat treated to develop an optimized microstructure in the dual alloy attachment section. The polycrystalline material in the attachment section may be machined to a firtree shape for mounting in a turbine wheel. The resulting turbine blade has improved life resulting from reduced low cycle, low temperature fatigue susceptibility of, and crack growth in, the composite attachment section.

Abstract: There are described MCrAlY type coating alloys having improved hot corrosion resistance, especially to sulfur and/or halide bearing compounds. In particular, improved hot corrosion resistance is achieved by the inclusion of about 1 to 12 weight percent titanium in the MCrAlY alloy composition.